The present invention relates to a device for stopping a loom when a filling thread is not introduced during the weaving operation, having a thread sensor arranged on a reed in order to detect the presence or absence of the last filling thread introduced and having a control member or means actuatable by the absence of the filling thread in order to shut down the loom.
In one known filling stop motion device for a loom, the thread sensor is developed as a U-shaped wire which is firmly clamped to the reed and forms a part of an electric circuit for the shutting down of the loom. The other part of this electric circuit comprises a contact member which is firmly mounted on the loom within the path of movement of the U-shaped wire. Upon the beating-up movement of the reed, the U-shaped wire is moved against the contact member. If the last filling thread introduced is present, then it prevents the U-shaped wire from contacting the contact member. If the last filling thread introduced is absent, then the U-shaped wire comes against the contact member whereby the electric circuit is closed and the loom is shut down.
Since the U-shaped wire which is clamped on the upper edge of the reed and extends downward into the plane of the filling thread consists of relatively thin wire and thus is of only slight rigidity there is no assurance that the U-shaped wire will come against the contact member. Furthermore, the dirt which unavoidably collects over a period of time impairs the making of a dependable contact between the U-shaped wire and the contact member. Furthermore, the fact that the U-shaped wire forms the thread sensor and also actuates the contact member constitutes a disadvantage, since this twofold function means that the U-shaped wire cannot be optimally adapted to each of the two functions it must perform in order to reliably sense the absence of a filling thread.
The closest prior art known to the applicants in connection with this application is in U.S. Pat. No. 3,442,301.